Identifying rainfall effects in an arid Gulf of California coastal lagoon

At Ensenada de La Paz, a coastal lagoon on the western side of the Gulf of California, nutrient and salinity data before and after rain events were evaluated using a mass balance model to estimate the exchange of conservative and non-conservative variables with the adjacent sea. Surface salinity, nitrogen (N-NO3, N-NO2), and phosphorus (PO4) were used in the model to obtain the hydraulic balance, water residence time, and nitrogen and phosphorus fluxes. Results showed that residual volume was mainly influenced by evaporation. Rainfall and runoff increased the mixed volume and reduced water residence time. Pre-rainfall hydraulic balance conditions were reestablished about 10 days after a rain storm. Rainwater inputs also modified the quality of the coastal lagoon: the pre-rainfall scenario showed that more nitrogen is consumed than produced, and there is a phosphorus sufficiency. A rain disturbance induces a nitrogen and phosphorus increase. Eleven days after a rain storm, nitrogen and phosphorus levels did not return to the pre-rainfall scenario. Rain disturbances in arid zone coastal lagoons modify their water quality and exchange with the adjacent ocean; some management strategies are suggested.     

From farming families to scavengers: a case study in the outskirts of Belém in the state of Pará

 In the middle of the 1970s, the introduction of large industrial and agricultural projects in Brazilian Amazonia created a situation of violence and loss of land used by farming families. In this context, the process of migration to the metropolitan region of Belém, which is principally in the interior of the state of Pará, was intensified. Excluded by the formal labor market, these families started to collect disposed material as scavengers. The material collected is found in landfills, streets, and open dumping areas. The main purpose of this research is to understand the social and environmental relations inherent in collection and recycling activities in the Amazon Region. Received: August 19, 2001 / Accepted: November 21, 2001     

Importance of legislation for maintaining forests on private properties in the Brazilian Cerrado

Environment, Development and Sustainability - This paper evaluates compliance with environmental laws in the municipality of Sorriso and the impact of changing legislation on vegetation. To verify...     

Ecological and economic valuation of the Potengi estuary mangrove wetlands (NE,Brazil) using ancillary spatial data

This study aimed at the ecological-economic valuation of the Potengi estuary mangrove wetlands, based on the integration of spatial data (mangrove forest coverage map, Nautical Chart, Environmental Sensitivity Chart) with data from literature on the biogeochemistry of nitrogen (N), phosphorus (P), and heavy metals in the mangrove estuary wetland Potengi) and field verification data (topographic profile of mangrove forest, GPS routes obtained in the field in the touristy sightseeing areas and plots of mariculture). The ecological and economic valuation of the services performed by the Potengi estuary mangrove wetlands, mainly as biogeochemical barrier for the transport of P, N and heavy metals in tropical coastal areas, were obtained just as if the retention of those elements was necessary by Wastewater Treatment Plants (WTP) with Stabilization Ponds, typical in the estuary, and Zeolitic plant, respectively. Closer to real scenarios were observed for obtaining the values of these ecological services, such as the release of the P, N and heavy metals in domestic and industrial sewage in the estuary, the capability of dilution and the influence of the tides in the estuary. The tourism potential of the Potengi estuary mangrove wetlands were assessed according to the current forms of use, and potential of aquaculture through the main types of farming in mangrove areas. For these ecological services, considerable values were obtained of about USS15,500/ha, such as costs of implementation and construction of sewage treatment plants, as well as costs of sewage treatment plants. Nearly US$ 12.500 / ha amount each year from tourism and aquaculture income, demonstrating the economic viability of the Potengi estuary mangrove wetlands conservation.